


Within a Mountain

by sal_amander



Series: His Grey Wings [5]
Category: Harry Potter - J. K. Rowling, Undertale (Video Game)
Genre: Angst, Frisk Needs A Hug, Frisks not so great home life, Master of Death (Harry Potter), Master of Death Harry Potter, MoD Harry, MoD!Harry, harry adopts a kid, well- another one
Language: English
Status: In-Progress
Published: 2019-12-16
Updated: 2020-10-26
Packaged: 2021-02-25 22:26:50
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings, Graphic Depictions Of Violence, Major Character Death
Chapters: 2
Words: 3,792
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21822883
Author URL: https://archiveofourown.org/users/sal_amander/pseuds/sal_amander
Summary: A fall from that height would kill any kid, no less a five year old. The script starts right after, though, and there’s no way in the hells Harry’s going to let them wander around alone. So, he takes this universe into his hands a bit more than most others. But with this kid, who can blame him?Or: Harry adopts another kid and helps them around the Underground, as a responsible adult should.(Id recommend reading the rest of the series first!)
Series: His Grey Wings [5]
Series URL: https://archiveofourown.org/series/1476032
Comments: 5
Kudos: 96





	1. Headrest

**Author's Note:**

> Yo, heads up, this gets dark from the start! You’ve been warned, and be safe!

It was dusk when the shouting started up again. Frisk’s foster family was by no means healthy. Madaline would mess dinner up, or get home a bit too late, and Ross would get pissed and start yelling. Then Madaline would start yelling back. Then Ross would break something, and Madaline would scream, and he would pull her into their bedroom, and all Frisk heard after that was Madaline sobbing.

Frisk knew what was happening in that room. They would hear Madaline talking to a picture frame about what happened, or a toothbrush, or a mug, or- or… Anything near her.

But she never got anyone to help her.

She was always so sweet to Frisk after a fight. Take them out to ice cream or some other treat, anything to get out of the house. She’d always use the right pronouns while they were out, but they both knew when they got back, it’d be back to being  _ sheherhers.  _ But Frisk understood. As much as a five year old could, they understood.

The fight started as usual. Madaline took a bit too long to get the groceries, and Ross was pissed. This time though, after the initial shout of  _ ‘Where the FUCK have you been, you shit?!” _ he was quiet. He stared at Madaline, who was cowering on the floor, for a moment, and then he turned to the other side of the kitchen.

The knife block.

He grabbed a fillet knife, sharpest one in there, and drove it straight through her throat, not giving Madaline a chance to scream. She crumpled with a thud, and stopped breathing.

Frisk was hyperventilating, backing up from the room.

A misplaced elbow, and they banged into the doorway. Ross turned swiftly, glowering at Frisk. He walked over slowly, and Frisk was petrified.

He grabbed their sweater and pulled them closer, and tried to plunge the knife into their left eye, but Frisk turned their head, and the knife drug against their face and right eye.

Frisk screamed, and clawed at the hand holding them. Ross growled something, but Frisk honed in on the knife in his hand. They darted their own hands out and managed to grab it, and stabbed it into Ross’ hand, freeing them. They were quick dash out the door and down the streets where they know Ross wouldn’t follow.

Down the streets at night, no one gave them a second glance as they ran. To the edge of the town. Over the fence. Into the woods.

Up the mountain.

Frisk was running away. 

The thought only hit them just now.

From the city. From the house. From their foster family. From all of it.

Their feet pounded the ground, and a hand held their bangs out of their eyes- one dark brown, and one closed, blood leaking out and staining their face and clothes. Their other hand was held in front, swatting away branches and leaves. Thin cuts were left on their hand, and tore at their sleeve, but they kept pressing on.

Up the mountain, away from  _ them _ .

A cave was up ahead, just at the peak, and they entered just as the patter of rain started up.

They let out a sigh, sliding down the oddly smoothe wall of the cave, curling up in a ball. They fell asleep soon after.

* * *

Frisk awoke to the sound of birds, and sunlight from the mouth of the cave. It finished raining earlier in the night, and it smelled of mud and dew.

They scrunched their face, and felt flakes of dried blood crinkle and break. Fresh blood started oozing out of the gash, and their eye was almost numb with pain.

They got up slowly, bracing themself on the wall. The world was spinning from the blood loss, and they took a few shaky steps backwards. A few was all it took, though, and they put their weight right into empty space.

As they fell, they didn’t scream. They didn’t cry. They just looked above as they fell, taking in the circle of light as it got smaller and smaller.

Their head hit the ground with a sick, wet crack, deafening the room for a moment. Golden flowers were splattered with blood, and a limp body crushed them. It looked like a halo of red, almost, from Frisk’s head, and one brown stared up, unseeing and lifeless.

And then, the eye did see. The eye saw a room with plants all around them, music was playing, and there was a tray of pastries that still looked hot.

When Frisk reached out to take one, they noticed something off. It felt weird, watching their hand grab the pastry. Something they were… Missing? 

Their free hand reached up, and felt along the scar -it had healed already?- across the right of their face, over their eye.

They closed their left eye, and kept their right open. 

They couldn’t see anything.

They almost dropped their pastry, eye flying open. They downed the pastry, tears welling up. They didn’t- they  _ couldn’t- _

Ok. This was going to be ok. They had to find out where they were and… and then what?

It didn’t matter right now, they decided, as any thoughtful five year old would, and got up to walk around.

After barely a moment of poking around plants and an old jukebox, a door opened, and they froze.

A man stepped out, in a purple apron that said  _ “Sizzle it up with -----,”  _ as if someone scratched the name out.  _ “Harry” _ was written above the name in white letters.

Frisk couldn’t help it, they giggled. And immediately clamped their hands over their mouth.

The man turned to them slowly, crouching down to their height, and spoke. “Hey, kiddo. You ok?”

Frisk stared, and slowly shook their head.

“Wanna talk about it?”

Frisk shook their head again, a bit more confidently this time. 

“That’s alright. My name’s Harry, what’s yours?”

Frisk thought a moment, and finger spelt ‘ _ F-R-I-S-K’ _ , and then signed  _ ‘you have your name on your…’  _ they stopped, and spelt out  _ ‘A-P-R-O-N’ _

Harry let out a small “oh,” and nodded, and showed them the sign for apron. Frisk copied and smiled.  _ ‘Deaf, hard of hearing, or mute?’ _

_ ‘Mute’ _

Harry nodded.  _ ‘Is it alright if I speak out loud?’ _

Frisk nodded vigorously, and Harry smiled. “Nice to meet you, Frisk. I assume you know what… happened?”

Frisk turned to the door that appeared out of nowhere, and back to Harry.  _ ‘I… died?’ _

Harry winced, but nodded. “I'm here to give you two options. You can go to the afterlife, or you can come with me, to keep the balance of the worlds in check, though I won’t put that on you until your older-” he paused, and frowned. “Well- scratch that, apparently your role in your world starts basically  _ now _ . So, if you choose this option, I’ll help you out with it.”

_ ‘I…’ _

Frisk looked away, and then back at Harry a few times, hand raising and dropping.

_ ‘I don’t wanna die…’ _

Harry nodded slowly, smiling.

“Very few truly do, kid. C’mon.” He stood, and raised his arms out, silently asking if Frisk wanted to be picked up. Frisk raised their arms up, and Harry picked them up, resting them on his him. He walked through the door, and there was a sweet scent in the air.

“We were baking a few pastries, you saw the ones in the lobby?” 

Frisk nodded, and Harry took them down the hall of bedrooms. A new door appeared quietly, and Harry brought them in. The room was done up in shades of green and orange, and had a bed with a curtain on it, and a large crate with plush toys, blocks, and other things that children like. There was a door inside that led to the bathroom, painted an olive green.

“You like it?”

Frisk nodded, and Harry set them down so Frisk could explore the new room.

“You can come here anytime you want, just wish for the door, and It’ll appear. Don’t go into other people’s rooms, you’ll see them labeled, unless you’re invited, but if i’m in my room, feel free to come get me, ok?

Frisk smiled at him, and Harry smiled back.

A knock came from the doorway, and Dave stood, confused but smiling. “New kid?”

Harry nodded. “This is your new sibling. Dave, meet Frisk. Frisk, meet Dave.”

Dave chuckled, sitting down to their height. “Howdy, then. Nice to meet ya, new sibling.”

Frisk smiled.  _ ‘Nice to meet you too, new brother.’ _

Dave blinked, scratching the back of his head. “I- don’t know ASL, sorry, can ya’ll-” he turned up to Harry, “...teach me?”

Harry nodded, smiling. 

“Pro’lly not right now though, I think im’boutta pass out from needing sleep.”

Harry just raised his eyebrow. “I thought you were watching the time?”

Dave waved his hand side to side, walking out. “Eeh, g’night!”

Frisk turned to Harry, and he shrugged. 

“Oh, before I forget-”

He snapped his fingers, and suddenly, there was a new weight on Frisks back. They turned, and two silvery grey wings were resting on their back.

They turned to him questioningly, and Harry smiled sheepishly. “My, balancers? Family? They have something to signify their relation to me, the grey wings.

Frisk just nodded, and Harry bent down, reaching his hand out. “So, we have a universe to play through, don’t we?”

Frisk nodded again, taking his hand, and suddenly, they weren’t in their room, they were in a cave with oddly purple stone, and yellow flowers.


	2. Chapter 2

**Notes for the Chapter:**

> Passing the ruins when your posing as two lost monsters.

Harry chewed his lip anxiously. It had been around a month since Frisk came to him. He could feel the strain of keeping that universe on pause, and it  _ hurt _ . The muscles going down his back ached, and he could barely move his wings when they were out. He looked like shit, too, and even Grif could see that, if the lilikoi jam left with a note for him was any hint.

He was going to have to unpause the universe again, but he had hoped to give Frisk a bit more time to recover, and get used to not having depth perception as well. 

Frisk and Dave had gone ‘outside’ earlier, to the bridging plane that Harry had created. Dave had recreated a ship that some of his friends had once used, he had told him as they were leaving- a bright golden one that Harry recognised from in some of Dave’s paintings. They were flying around the plane, looking for a nice place to build a ‘club house’ apparently. Harry thought it was cute, and ushered them out. He probably should have told them to wait, and completed Frisk’s universe role with them beforehand, but ah, well. 

He focused for a second, pinpointing them on one of the floating islands, the center most of a cluster of five. A moment later, and with the sound of a hundred wings, he appeared next to them. He winced, wings sliding back into incorporealness, and turned to them.

“Nice spot, hmm?”

Frisk and Dave brightened when they noticed him, and Frisk nodded enthusiastically. Dave smiled, gesturing to the outer islands.

“Yeah, we’re thinking about the main building being here in the center, but on each island, we’ll have other stuff. I know we’ll need a building for tools and supplies for adventuring, and another for all the cool stuff we find- and maybe one for building stuff? But the rest, I dunno…” 

Frisk tugged on his sleeve, and signed  _ ‘what about a cabin? Like, with bunk-beds and everything, just for fun?’ _

Dave took a moment to watch, and after a moment of mentally translating, nodded. “A cabin?” He saw Frisk’s nod, and continued. “Sounds nice, and It’d be good if we want a short change of scenery- oh! Or if we have friends over or anything. Good idea.”

Frisk beamed, and turned to Harry, who in turn ruffled their hair.

“So, Frisk,” Harry bent down, taking a seat on the ground. “You know how your universe is due to unpause soon?”

Frisk nodded, sitting down in front of him. Harry nodded to Dave, who nodded back and summoned his door to leave them alone.

“I think we need to go soon. Like, within the next few minutes to an hour, soon. Is that alright?”

Frisk thought a moment, then nodded, signing  _ ‘I know I fell… will we go there?” _

Harry smiled. “Yes, we will. You need to know though, in your universe, monsters live down there.”

Frisk made an almost distressed frown, and Harry hastily added “Not that type- its a species. They’re generally pretty non-violent, and only few have seen humans. I’ll disguise us anyway, just to be safe. Is that alright?”

Frisk thought a moment, and cocked their head, hands moving.  _ ‘How?’ _

“Well…” Harry hummed, standing up and transforming himself. He had two pairs of his silvery grey wings out, and feathers appeared around his chin and the sides of his face and neck. His arms grew black and scaly from his hands up to his elbow, and nails grew into talons, and his legs and feet took a similar pattern. A sharp pain in his wings reminded him of the task at hand, and he turned to Frisk. “For you, I’d just have your wings out temporarily permanent, and make your nails a bit more talon-like, if that is alright?”

Now, Frisk looked excited, and nodded enthusiastically, standing and pulling their wings out, a somewhat duller and less ethereal grey that Harry’s, but still sleek. They held their hands out for Harry to change, and when he moved a bit too fast, they barely flinched. 

A major improvement.

A brush of his fingers, and Frisk’s nails grey longer, harder, and sharper, and they could feel something settle into their wings when Harry brushed his hands over them. “Just a precaution, so you don’t accidentally tuck them in.”

Frisk nodded.

“Now, when you take my hand, we’ll appear where you fell, when you fell, alright?”

Frisk nodded, and took his hand, and they were whisked away to their universe, sounding of feathers and a flutter of paper as a note appeared on the fridge to let Dave know what they were doing.

\---

They opened their eyes to sunlight filtering down on their faces from the top of the cavern. How the light got past the cave and into the pit was something neither of them knew, nor did they want to think too hard on it. 

“You good, kiddo?”

Frisk nodded, wings fluffing a bit. 

Harry spread his own wings out, now feeling tight and sore after so much stress on them. He worked the muscles for a bit, fanning his wings and beating them in and out. A final shudder of them, and they closed loosley, still feeling tight, but much better than before.

He turned to Frisk, smiling and nodding to the next cavern’s entrance. “Ready?”

Frisk nodded, puffing up and walking just ahead of Harry, who chuckled. The hallway was dim, borderline dark, aside from a stream of sunlight surrounding a sunflower. 

When the sunflower moved, however, Harry pulled Frisk behind him. Just in case. 

The sunflower opened two dark eyes and turned to look at them, and a mouth pulled into a grin for a second, then faded just a bit. “Never seen you two before, I thought she kept the doors shut.”

The comment seemed to have a tone dripping with boredom and wasn’t phrased as a question at all, but Harry answered. “Ah- about that. My kid was showing me something they figured out with their magic, something went wrong, and we appeared here- well, past the hallway, technically. Where is this, exactly?”

The flower stared at them for a moment, then shook his head, “eh, Im tired,” and proceded to start burrowing, but not before popping up and stating “Queen’s coming, ask her.”

The flower was gone barley a moment later, making Harry frown. “Rude,” he muttered, turning to Frisk. “So, should we stay and ask questions, or start walking?”

Frisk signed  _ ‘walk’ _ decisively, and Harry snickered, nodding. “C’mon then, who knows how far we’ll have to walk to find the exit.” Frisk nodded, darting in front again and picking up a stick by the walls of the cavern and holding it up as if it were a flag, smiling.

Harry chuckled. “Lead the way, Frisk.”

Frisk grinned at him, and started forwards, waving the stick as if it held a banner or a torch. They arrived at a puzzle quickly, and Harry let Frisk work it out- and they did so fairly easily. All you had to do was step on certain tiles.

Just as the doors opened and Frisk dashed in, however, they ran into something solid and fluffy. They pulled back, took a look at the monster they quite literally ran into, and ran to hide behind Harry. Harry’s wings unfurled slightly, hiding the kid from view, and he looked up at the monster.

A tall, white goat creature, standing and looking quite surprised, wearing a purple dress and robe. “O-oh, I’m sorry about that-” She began to say, but Harry shook his head, finding the monster to be nonviolent. “T’s alright, they aren’t used to seeing too many monsters.”

The goat woman turned her head slightly. “I… haven’t seen you two around here before?”

Harry blinked, feigning slight awkwardness, and his wings curled back a bit more to comfort Frisk. “Ah, no, um- my kid’s magic accidentally brought us here-” he paused, looking at the woman’s impressive look, “we live- um, where are we, exactly?”

The woman bit back a laugh, and smiled at them, “Ah, that makes sense, no one’s entered or exited here for… a long time. You’re in the ruins currently, just near the entrance to the mountain.”

Harry nodded, looking around and not meeting the woman’s eyes. “How do we get- er, in?”

The woman clapped her hands- well, paws together. “Oh! Right. The entrance is below my home. I’ll take you there.”

Harry thanked her, and turned to pick Frisk up, who held onto the sweater he was wearing tightly, but was slightly more open to the goat woman. They waved, and the goat woman waved back.

“So, I guess we should introduce ourselves? I’m Harry, and this is my kid, Frisk.”

The goat woman looked apologetic. “I should have probably started with that, I’m sorry. I’m Toriel, caretaker of the Ruins.”

They made smalltalk as they walked through the ruins, Toriel shutting off the puzzles so they could go through quicker. 

They were walking through a few tunnels when toriel turned to them as she walked. “Ah, as you can probably tell, I don’t get too many visitors here. Do you think you’ll have enough time to stay for dinner? I understand if you don’t…”

Harry looked to Frisk to see if they’d be open to it, and as they nodded, he turned to her. “We both don’t mind, we can spend a bit more time here.”

Toriel brightened. “Oh, wonderful! Anything you’d like, specifically?”

They both shook their heads, but Harry spoke up. “No, but I would like to help cook, if that is alright with you?”

Toriel nodded, and they entered a wide cavern with a tree dead center, and a house a bit behind it. “Here we are,” she said brightly, unlocking the door and letting them in. 

Frisk immediately went to the bookshelf and pulled out a book on history, leaving Harry and Toriel to giggle at them. The two entered the kitchen, and Toriel looked through some cabinets, frowning. “Well, it seems as if i'm out of snails, and I don’t really have the time to collect more, so…”

She sifted through the fridge and a few more cabinets, pulling out a few ingredients, and turned to Harry, handing him a recipe to look at. “How about butterscotch-cinnamon pie?”

Harry smiled, “Sounds great, how can I help?”

After a bit of explaining on Toriel's half, they started preparing the pie, and half an hour later, it was put in the oven to cook for a bit.

When they walked back into the living room, they found Frisk lying down, almost completing the large history textbook they had started earlier. Toriel blinked in surprise, sitting down on her chair, but Harry just shook his head, sitting criss cross next to Frisk.

They looked up, closing the book, and smiled, signing rapid fire about what they had learned. At the angel Toriel was at, she couldn’t see what they were signing, but she smiled anyway.

Harry watched Frisk’s hands avidly, nodding and asking a few questions here and there- making sure to phrase them as if *he* knew the answer, and wanted to make sure Frisk knew. After a few minutes, Frisk went back to the book, and Harry double checked the info with the Universe backlog running through his consciousness. For a history book, it was actually pretty accurate.

Toriel gave a hum, tilting her head. “So, Harry. How are things in New Home?”

Harry paused, reaching into the backlog for answers. “Well, I don’t live around there- we’re pretty secluded in… Waterfall. But when I do pop in, it seems to be as bustling as ever…?”   
  
Waterfall was winding and maze-like. It wouldn’t be unheard of for a monster and his kid to hermit out, there. Easy.

His voice seemed unsure, but Toriel took it as general nervousness and didn’t think much on it. “I should pop in again, soon… it’s been a long time.” She said quietly, leaning back in her chair. The fire crackled behind them, and Frisk finished the history book and re-shelved it, walking back to Harry. They seemed to doze, falling into his arms sleepily. Almost on que, the pie timer dinged, signaling it was time to eat.

Frisk seemed far too tired, so Toriel showed them the guest room, and Harry tucked them in, exiting. Toriel seemed confused, and Harry just smiled. “I let them pick when they eat, as long as they eat three meals and some snacks a day. It’s helped them a lot.”

Toriel still seemed confused, but the two made their way to the dinner table, eating in relative silence. Harry took a piece to save for Frisk later, and when Toriel retired to bed, as Frisk hadn’t awoken, Harry took the chair. He didn’t sleep, he focused on exercising his wings, the four stretching and maneuvering awkwardly.

By the next morning, they were almost as good as new with the energy he laid in them, and Frisk was ready to go.

Toriel seemed almost sad when they left, and they opened the final door to a cold, snowy environment.

**Author's Note:**

> This is short, I know! Sorry,,,


End file.
